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536EX Chipset Developer’s Manual 71
Intel Confidential
IS-101 Voice Mode AT Commands
6.1 DTMF Detection Reporting
DTMF detection information is reported by the modem to the DTE by a <DLE> shielded command
as outlined in Section 6.5 of the ITU V.253 specification. When the DTMF burst is detected in
Voice mode, the modem sends to the DTE a <DLE></> followed by a sequence of <DLE><-> is
inserted to indicate the end of the determination interval.
For example, a single 280ms burst of DTMF 5 would report:
<DLE></><DLE><5><DLE><5><DLE><5><DLE><5><DLE><->
6.2 Relay Control
To originate a call (that is, to originate call forwarding or auto-dialing) and to generate tones, use
the dialing command:
ATDT <telephone number>
If the modem was not already off-hook, then this command automatically configures the value for
AT+VLS=m to m = 1 or m = 5 depending on the value for Mn.
To answer a call, use the AT+VLS=m command. Unlike data mode, the modem (when configured
for voice mode) does not automatically answer an incoming call (that is, the modem ignores the
contents of S-register S0).
Remote playback/record takes place whenever the modem is off-hook (OHREL* is activated). For
local playback/record, the modem is on-hook, and the user uses a local telephone or handset. The
LPHREL* relay driver may be used to control the local telephone or handset when implementing
local playback/record mode (AT+VLS=m). Additionally, voice messages may be played through
the modem/computer speaker. The 536EX chipsets also provide a microphone interface that can be
used for local recording.
In voice mode, all voice AT commands can be issued by the DTE at any valid speed between 300
bps to 115,200 bps. Typically, the DTE-to-modem data rate is set for 19,200 bps, which is the
recommended data rate for Class 1 fax mode. The DTE-to-modem data rate may need to be set to
115,200 bps in certain instances, such as during playback or during record mode for a CL1
compression scheme.
The following data and fax AT commands are supported in voice mode:
Data: All except ATA, ATIn
Fax: +FCLASS
Table 25. Voice Mode Command Descriptions
Command Default Description
+FCLASS
=8
0
Voice Mode Selection: This command enables or disables voice mode. All voice mode commands
(except for +FCLASS=m) are valid only in voice mode.
0* Data mode
1 Class 1 fax mode
8 Voice mode enabled
NOTE: An asterisk (*) denotes the factory-default setting.